This invention relates to the use of catalysts comprising certain stabilized, reduced metal complexes in the polymerization of olefin polymers. In one embodiment such catalysts additionally employ an activating cocatalyst. In another embodiment such catalysts may be employed with or without an activating cocatalyst. Finally the invention relates to an improved method for preparing the stabilized reduced metal complexes. The compositions are especially useful as catalysts for the polymerization of olefins such as ethylene for polymers having utility as molding resins and in the formation of foamed products having cushioning and insulating applications and films that are useful as protective wrappings.
In U.S. Ser. No. 545,403, filed Jul. 3, 1990 (equivalent to EP-A-416,815) there are disclosed and claimed certain monocyclopentadienyl metal complexes having utility as homogeneous olefin polymerization catalysts. In U.S. Pat. No. 5,064,802 (equivalent to EP-A-418,044), cationic monocyclopentadienyl metal complexes with salts of Bronsted acids containing a non-coordinating compatible anion are disclosed and claimed. Finally, in U.S. Ser. No. 547,718, also filed on July 3, 1990 now abandoned (EP-A-468,651), an oxidative activation technique for preparing such cationic catalysts is disclosed and claimed. For the teachings contained therein the above mentioned pending U.S. applications and U.S. patent are herein incorporated in their entirety by reference thereto.
In J. Am. Chem. Soc. 113, 3623-3625 (1991) there is disclosed a process for preparation of "cation like" zirconocene polymerization complexes by alkyl abstraction using tris(pentafluorophenyl)borane. The complexes were stated to have activity roughly comparable to typical complexes employing alumoxane. No suggestion as to the suitability of the disclosed technique for use with reduced oxidation state metal catalysts is provided by the reference.
In U.S. Pat. No. 4,057,565 there are disclosed Ti, Zr, or Hf derivatives of 2-dialkylaminobenzyl or 2-dialkylaminomethylphenyl all in the +4 oxidation state which are useful as components of catalysts for olefin polymerization. No mention is given for +3 oxidation state metal catalysts.
In J. Am. Chem. Soc. 100, 8,068-8,073 (1978) there is mentioned the synthesis and characterization of Ti(+3) complexes containing cyclopentadienyl groups and 2-dialkylaminobenzyl or 2-dialkylaminomethylphenyl groups. No mention of utility as addition polymerization catalysts is given.
In U.S. Pat. No. 4,870,042, catalysts for olefin polymerizations comprising a pyrazolyl borate complex of titanium or zirconium compounds including titanium trichloride (Example 4) are disclosed.
In Organometallics, 10, 3227-3237 (1991) certain titanium +3 complexes containing cyclopentadienyl groups and alkyl groups are mentioned. On page 3236, the reference states:
"So far no well-defined neutral titanium-based molecular system with established activity for catalytic olefin polymerization has been described . . . Apparently, the tervalent Cp*.sub.2 TiR system cannot induce sufficient positive charge at the .beta.-carbon atom of an incoming ethylene molecule to reach the polar transition state for migratory insertion."
In Journal of Organometallic Chemistry, 334 (1987) C1-C4, .eta..sup.3 -allyl(bis-.eta..sup.5 -cyclopentadienyl)titanium (III) activated with dimethylaluminum chloride was found to create a coordinated species Cp.sub.2 Ti (allyl)--(CH.sub.3).sub.2 AlCl which was found to polymerize ethylene. Use of stronger Lewis acids so as to cause ligand abstraction thereby destroying the requisite carbon-titanium bond was to be avoided according to the reference.
In accordance with the present invention there is provided an addition polymerization catalyst comprising in combination:
a metal complex, A.sub.1, corresponding to the formula: EQU Cp.sub.2 ML, (Ia)
wherein:
Cp independently each occurrence is a cyclopentadienyl group .pi.-bound to M, or a hydrocarbyl, silyl, halo, halohydrocarbyl, hydrocarbylmetalloid or halohydrocarbylmetalloid substituted derivative of said cyclopentadienyl group, said Cp containing up to 50 nonhydrogen atoms, and optionally both Cp groups may be joined together by a bridging group;
M is a metal of Group 4 of the Periodic Table of the Elements in the .sup.+ 3 oxidation state;
L is a monovalent anionic stabilizing ligand selected from the group consisting of: alkyl, cycloalkyl, aryl, silyl, amido, phosphido, alkoxy, aryloxy, sulfido groups and mixtures thereof, and being further substituted with an amine, phosphine, ether, or thioether containing substituent able to form a coordinate-covalent bond or chelating bond with M; said ligand having up to 50 nonhydrogen atoms;
and an activating cocatalyst.
Preferably in accordance with the present invention the ratio of metal complex to activating cocatalyst is from 1:0.01 to 1:10.sup.6.
In a further embodiment there is provided an addition polymerization catalyst comprising in combination:
a metal complex, A.sub.2, corresponding to the formula EQU Cp'ML'.sub.2, (Ib)
wherein:
Cp' is a cyclopentadienyl group, or a hydrocarbyl, silyl, halo, halohydrocarbyl, or hydrocarbylmetalloid substituted derivative thereof, said Cp' containing up to 50 nonhydrogen atoms;
M is a metal of Group 4 of the Periodic Table of the Elements in the .sup.+ 3 oxidation state;
L' independently each occurrence is hydride, halo, or a monovalent anionic ligand selected from the group consisting of hydrocarbyl, silyl, amido, phosphido, alkoxy, aryloxy, and sulfido groups; mixtures thereof; and amine, phosphine, ether, and thioether derivatives of the foregoing, said ligand having up to 50 nonhydrogen atoms, with the proviso that in at least one occurrence L' is a stabilizing ligand comprising an amine, phosphine, ether or thioether functionality able to form a coordinate-covalent bond or chelating bond with M, or comprising an ethylenic unsaturation able to form an .eta.3 bond with M;
and an activating cocatalyst.
Preferably the activating cocatalyst is present in an amount to provide a ratio of metal complex to activating cocatalyst from 1:0.01 to 1:10.sup.6.
In a still further embodiment of the present invention there is provided a metal complex, A.sub.3, corresponding to the formula: ##STR1## wherein:
M is a metal of Group 4 of the Periodic Table of the Elements in the .sup.+ 3 oxidation state;
Cp" is a cyclopentadienyl group, or a hydrocarbyl, silyl, halo, halohydrocarbyl, or hydrocarbylmetalloid substituted derivative thereof, said Cp" containing up to 50 nonhydrogen atoms;
Z is a divalent moiety comprising oxygen, nitrogen, phosphorous, boron, or a member of Group 14 of the Periodic Table of the Elements said moiety having up to 30 nonhydrogen atoms;
Y is a linking group comprising nitrogen, phosphorus, oxygen or sulfur covalently bonded to M and Z through said nitrogen, phosphorus, oxygen or sulfur atom, the ligand moiety consisting of --Cp"--Z--Y-- being dianionic and having the ionic charges residing formally on Cp" and Y; and
L" is a stabilizing ligand selected from the group consisting of L and C.sub.3-10 hydrocarbyl groups comprising an ethylenic unsaturation able to form an .eta.3 bond with M.
The above complexes, A.sub.3, are suitable for use in polymerization of addition polymerizable monomers alone or optionally in the presence of an activating cocatalyst. When present, the activating cocatalyst is preferably used in an amount to provide a ratio of metal complex to activating cocatalyst from 1:0.01 to 1:10.sup.6.